1. Field of the Invention
The present invention relates to an image processing method and an image processing apparatus which enable an operator to correct image data in the same manner as carrying out retouching work, and also to a computer-readable recording medium storing a program to cause a computer to execute the image processing method.
2. Description of the Related Art
In order to generate higher quality images, a photograph finishing system in a laboratory carries out printing after retouching work has been carried out directly on images recorded on an original negative or reversal film. For example, in the case of portrait photographing by using a negative film, retouching is carried out on an image of a person recorded on the film with a pencil along his/her nose so that the appearance of nose is sharpened. In the case where a reversal film is used, chroma of a specific subject in an image to be printed can be emphasized by superposing a color on the film by using a dedicated coloring material.
Meanwhile, following development of computer technology in recent years, printing systems for generating printed images after carrying out appropriate processing on image data obtained by reading an image recorded on a negative or reversal film or on image data obtained by photographing with a digital camera have been proposed. In such a printing system, since printing is carried out after image processing such as tone correction, brightness correction, and white balance correction has been carried out on the image data, high quality prints can be obtained even if photographing was not completely successful.
However, in the above-described photograph finishing system in a laboratory, films are directly manipulated and an operation for the manipulation is substantially complicated. Therefore, only skilled workers can carry out satisfactory processing. It is extremely difficult for a photographer who has photographed an image to be corrected to carry out retouching work directly on a film by himself/herself, and even a skilled worker may not necessarily reflect the photographer""s intention accurately in the printed image. Furthermore, although density increasing processing on a film to cause density of a printed image to become lower can be carried out, for example in the case of retouching a negative film, density decreasing processing on a film to cause density of a printed image to become higher cannot be carried out easily. Moreover, since films are manipulated directly, correction is not easily undone.
Meanwhile, image processing used in the above-described printing system is to correct entire image data by setting a parameter for tone correction or the like based on the image data. Therefore, sharpening only a person""s nose or emphasizing chroma of a specific subject, which are possible by using the photograph finishing system in a laboratory, are not possible by using the printing system.
The present invention has been created based on consideration of the above problems. An object of the present invention is to provide an image processing method and an image processing apparatus for enabling correction of image data in the same manner as by a photograph finishing system in a laboratory, and a computer-readable recording medium storing a program to cause a computer to execute the image processing method.
An image processing method of the present invention comprises the steps of:
obtaining corrected sub-image data by correcting at least a portion of sub-image data representing information included in an original image represented by main image data; and
obtaining processed image data by correcting the main image data based on the corrected sub-image data.
It is preferable for the image processing method of the present invention to correct the main image data only for a portion corrected in the sub-image data, based on the corrected sub-image data.
It is preferable for the corrected sub-image data to be obtained by reproducing the sub-image data on reproduction means and correcting the reproduced sub-image data.
The sub-image data may be generated from the main image data. Alternatively, in the case where the main image data have been obtained by photoelectrically reading the original image, the sub-image data may be generated by reading the original image separately from the main image data acquisition. Moreover, in the case where original images have been obtained by consecutively photographing one and the same subject, one of the original images may be the sub-image, and image data representing the sub-image can be the sub-image data.
As the sub-image data, density information of the main image data, information reversing the density information, chroma information of the main image data, and the like can be listed. However, depending on the content of a desired correction, various kinds of information can be used. When the original image is a negative image, the sub-image to be obtained by reproducing the sub-image data is a negative image. Meanwhile, when the original image is a positive image, a negative sub-image can be reproduced by reversing the density information.
The sub-image data may have a predetermined offset value. This is because the density cannot be lowered for a portion having 0 density, in the case where the density is corrected. In this case, by letting the offset value correspond to an orange color, the sub-image obtained by reproducing the sub-image data looks like an image recorded on a negative film. Furthermore, by representing the density information by the orange color, the sub-image looks like an image recorded on a negative film. Moreover, processing efficiency may be improved by letting the number of bits of the sub-image data be smaller than that of the original image data.
The corrected sub-image data and the main image data may be stored in a recording medium by relating the two.
An image processing apparatus of the present invention comprises:
corrected sub-image data generating means for obtaining corrected sub-image data by correcting at least a portion of sub-image data representing information included in an original image represented by main image data; and
correction means for obtaining processed image data by correcting the main image data based on the corrected sub-image data.
It is preferable for the image processing apparatus of the present invention to correct the main image data based on the corrected sub-image data, only for a portion corrected in the sub-image data.
It is also preferable for the corrected sub-image data generating means to comprise means for generating the sub-image data from the main image data.
Furthermore, it is preferable for the corrected sub-image data generating means to comprise:
reproduction means for reproducing the sub-image data; and
input means for allowing an input for correcting the reproduced sub-image data.
The processing carried out in the image processing method may be provided as a program to cause a computer to execute the processing recorded in a computer-readable recording medium.
According to the present invention, the corrected sub-image data are obtained by correcting at least a portion of the sub-image data representing density information, chroma information and the like of an original image, and the main image data are corrected based on the corrected sub-image data. Therefore, the same processing as in retouching work such as sharpening the image of a nose or emphasizing chroma of a specific subject is carried out on the sub-image data to obtain the corrected sub-image data, and based on the corrected sub-image data, the main image data are corrected. In this manner, the image obtained by reproducing the processed image data has been finished with the same processing as in the retouching work carried out by a photograph finishing system in a laboratory. By correcting the sub-image data in this manner, retouching work can be undone after generating the sub-image data again even when the correction was not successful. Therefore, a photographer can carry out the correction easily by himself/herself, and a corrected image reflecting the photographer""s intention accurately can be obtained. Since density is easily increased or decreased in the sub-image data, density increase or decrease of a printed image can be carried out more easily than on a film by using a photograph finishing system. Furthermore, a portion of an image, not the entire image, can be corrected easily.